Functions & info. of Thermal & Pressure Relief Valves 1

[mohd]

DEAR GENTLEMEN:

PLEASE...I HAVE QUESTION HERE...

I WOULD LIKE TO KNOW THE EXACT & DETAIL FUNCTION OF BOTH THERMAL(TRV) AND PRESSURE(PRV) RELIEF VALVE?
THROUGH THEIR FUNCTIONS, ANYONE KNOWS THE MAIN DIFFERENCES BETWEEN THEM, AND WHERE TO BE INSTALLED;
FOR EXAMPLE, I KNOW THAT TRV MUST BE INSTALLED IN ANY PIPE CIRCUIT THAT HAVING THE POSSIBILITY TO BLOCK IN...

AND, COULD YOU PLEASE ENHANCE MY KNOWLEDGE ON THE SUBJECT OF THE INTERACTION BET. THE TRV AND TWO PHASE FLOW>? HOW DO THEY RELATED..!! HOW DOES THE TWO PHASE FLOW EFFECT THE TRV FUNCTION OR SELECTION?
ANY REFERENCES... BOOKS... JOURNALS... PERIODIACALS
THANKS ALOT FREINDS,
BYE...

 

[BillBirch]

Why do you want to know this? If it is for general information I would suggest talking to manufactures such as AGCO (Tyco) or Dresser for catalogue information. If you need to know for a job, such as selecting these valves, I suggest you consult an experienced engineer. These are far too important items to be taken lightly. Regarding your question, I don't understand it!

Regards,

 

[mohd]

MANY THANKS BillBirch FOR YOUR QUIK REPLY,

I NEED TO SUCH INFO. FOR BOTH MY INFO. AS WELL JOB RELATED,

MY FIRST QUESTION WAS JUST QUARY OF MORE INFO. ABOUT THE ABOVE SUBJECT, AND

SECOND QUESTION WAS:\IN CASE YOU HAVE PIPELINE FILLED WITH CRUDE OIL AND SOME VAPOR AND AT THE SAME TIME SUBJECTED TO SOLAR HEATING, FOR SURE, PRESSURE WOULD RISE AND THEN EITHER IT OBSORBS BY THE PIPE OR THE PIPE WOULD REPTURED ONCE IT REACHS IT YIELD POINT, SO IS THE TWO PHASE FLOW HAS SOMETHING TO DO WITH THIS?

 

[ralphsare]

Have you tried the cheresources.com. If not go to the message board and select Relief Devices. There a prv guro there by the name of Phil Leckner who may take on your question.
Another resource ive used is the askache.com.

 

[TD2K]

If you have a pipeline containing crude oil and vapor, you need to look at the thermodynamics of the system using a process simulator or some other tool. Essentially, as the pipeline and its contents heat up, the vapor pressure of the crude will increase (what you would see as the pipeline prssure) and this must remain below the pipeline MAWP. The pressure is a function of your specific crude oil. Once you determine the pipeline CAN be overpressured, the amount of vapor to be relieved would be the latent heat of the fraction 'boiling' off into the vapor space divided by the heat input into the pipeline (I'm assuming the PSV is located on the line such that it only relieves vapor).

If it's a liquid filled line, the sizing is more straight forward and the pressure safety valve manuals (AGCO, Consolidated, etc) go through how to size these.

Typically, you'll find the thermal relief valves for liquid filled lines are minimum size unless you are talking about a very long line.

 

[svanels]

Practical, a PSV reliefs more fluid than a TRV, so the PSV is bigger in size.

You will find a PSV on :
1) high pressure systems like boilers and steam lines.
2) in the discharge line op a positive displacement pump. In many cases this is also built into the pump, but then it is just for flow control.

The TRV can be compared to an automatic vent valve to prevent pressure build up. Generally we install them between the pump suction and the tank in crude installations. Steven van Els
SAvanEls@cq-link.sr